This article explores the applications of research on native spoken language into second language learning in the concept of subordination. Second language (L2) learners' ability to integrate subordinate clauses is considered an indication of higher proficiency (e.g., Ellis & Barkhuizen, 2005; Tarone & Swierzbin, 2009). However, the notion of subordination is challenged in the analysis of spoken syntax due to the potential problems in identifying clausal relationships. The study compares the production of "if"-clauses of first language (L1; N = 20) and L2 (N = 20) speakers of English in informal conversations and a map task. Results show that L2 speakers exhibited a strong preference for pre-posed "if"-clauses consisting of one "if"-clause; compared to L1 users, they used few multiclausal "if"-clause complexes and postscript and semiformulaic post-posed clauses in the conversations. As for the map task, L2 speakers did not use single "if"-clause directives, frequently used by L1 speakers. The findings seem to indicate that L2 speakers were constrained in their structural and hence functional repertoire. The article concludes that using subordination as a measure of complexity may not be straightforward, because clausal relations typical of spoken language need to be taken into account.